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DIY Guide: How To Replace The Opti-Spark And Water Pump On Your C4

[CorvSport Curated Guide Series] This how-to gives you all the steps to replace the Opti-Spark and water pump on your C4

Welcome to the continuation of a new DIY series where CorvSport canvasses the internet for the best do-it-yourself guides. Let CorvSport be your digital encyclopedia and bring you the best guides and resources from our vast Corvette community. This series can also give an enthusiast contemplating a DIY project the clarity needed to realize they should hire an expert.

Nearly every generation has at least one component that enthusiasts are urged to proactively replace due to some inherent issue. You’ll hear something like this: “If you don’t replace that now, it’s going to fail at the worst time and cause damage!” For instance, with the C5, that component is the harmonic balancer, and we’ve published a guide for that DIY fix here. For the fourth-generation Corvette, that component is the Opti-Spark. And today’s guide will also include a “while you’re in there” component, the water pump.

CorvSport Complexity Guide

  • Difficulty: 7 (10 most difficult)
  • Patience Needed: 9
  • Level of Specialty Tools Required: 5
  • Is a Helper Recommended? No

Today’s guide comes from Corvette Forum member “LT1*C4” and is the best and most comprehensive guide I could find on the internet. To augment this guide, I’ve also included a highly recommended YouTube video. This curated C4 Opti-Spark and water pump replacement is fully credited to “LT1*C4” and is being presented to our CorvSport community in an unedited format. You’ll note in these steps that LT1*C4 took the time to put the detailed instructions in the pictures.

How To Replace The Opti-Spark And Water Pump On Your C4

Step 1: Disconnect the battery

Step 2: Drain the engine coolant

Step 3: Unplug the IAT sensor

Step 4: Gain access to the throttle body and water pump

Step 5: Remove the coil wire

Step 6: Remove the passenger-side hose

Step 7: Unplug the IAC valve

Step 8: Remove the TPS sensor

Step 9: Remove the vacuum line

Step 10: Remove the coolant hoses

Step 11: Remove the throttle cable

Step 12: Remove the throttle body

Step 13: Preparation for water pump removal

Step 14: Disconnect the ECT sensor

Step 15: Remove the connection to the Opti-Spark

Step 16: Remove the serpentine belt

Step 17: Remove the water pump

Step 18: Remove the plug wires

Step 19: Remove the crank pulley

Step 20: You’re halfway done; time for some cleaning

Step 21: Check the weep hole on your water pump (if not replacing with a new one)

Step 22: Electric water pump installation preparation

Step 23: Opti-Spark preparation and installation

Step 24: Pulley reinstallation

Step 25: Opti-Spark preparation and installation

Step 26: Reinstall the plug wires

Step 27: Prepare and install the water pump

Step 28: Reinstall the 6 cover bolts

Step 29: Bypass the throttle body coolant (optional)

Step 30: Refill your coolant system

The End! If you want to keep up to date with all the fresh Corvette news and maintain a pulse on the lifestyle and culture of this exciting, iconic brand, CorvSport has the fastest-growing Corvette community on our Facebook page, with over 173,000 followers (54,000 since January 2023!). Come join other hardcore enthusiasts and say hello, Douglas B.

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